Inhaled intrapartum analgesia using a 50-50 %mixture of nitrous oxide-oxygen in a low-income hospital setting

Aim To analyze the benefits of an inhaled analgesia procedure over intrapartum pain and the degree of satisfaction of using this method. Methods This was a pilot study carried out at a lowincome hospital setting in which women with singleton pregnancies, cephalic presentation and active phase of labor were requested to inhale ad libitum a 50-50 % mixture of nitrous oxide and oxygen (N₂O-O₂) (Oxicalm®, Indura S.A-Indura Ecuador) using a face mask with an auto-demand valve. Effect over labor pain and dynamics and side effects were recorded. Results A total of 126 gravids participated with a mean age of 21.6 ± 6.7 years, 50.8 % of which were adolescents. As assessed by the Visual Analog Scale 1 h after initiating the procedure pain significantly decreased 56.2 % on average (8.9-4.9 points, p = 0.001), while increasing cervical dilation and effacement by 28.4 and 21.7 %, respectively. Overall vaginal delivery was achieved in 96.9 % of cases, with an average procedure initiation to delivery time interval of 2 ± 1 h and mixture consumption of 0.93 kg. Vaginal delivery rates were 36.5, 78.6 and 89.7 % for the first, second and third hour, respectively. During that time maternal hemodynamic parameters remained unaltered. Mean duration of the second stage of delivery was 6.2 min. Obstetrical and neonatal outcome was otherwise favorable. Main adverse effect of using the mixture was dizziness (43.7 %) referred by gravids as mild and tolerable. A 96 % of users answered that they would recommend the method and graded it in 92.9 % as good/ excellent. Conclusion Inhaled intrapartum analgesia using a N2O-O2 50-50 % mixture provided rapid pain alleviation. It is an appealing, effective and safe method for the management of pain during labor, most useful at institutions with infrastructure and personnel limitations.